1. Field of the Invention
The present invention relates to a machine tool including a machine body machining a workpiece, a machine body cover covering a periphery of the machine body, and a door device capable of opening/closing a machining-area opening formed in the machine body cover.
2. Description of the Related Art
In machine tools such as a lathe, a structure, in which the periphery of a machine body is surrounded by a machine body cover provided with a machining-area opening a machining area to be machined to outside and the machining-area opening is covered by a door in an openable/closable manner, is adopted.
It is designed to prevent the workpiece from jumping to outside by covering the machining-area opening by the door, even when the workpiece is disengaged from a chuck in the course of the machining. In conventional machine tools, in general, a window is provided in the above-described door so that the inside status of the machining area can be observed from outside when machining the workpiece (for example, refer to Patent document 1).    [Patent document 1] Utility Model Registration No. 3103602
Meanwhile, since the above-described door is needed to be formed staunch enough to endure and not to break even when the workpiece jumps out to give a blow, the window to observe the inside is forced to be set to have the smallest size. Therefore, for example, it is limited to observe the inside status of the machining area sufficiently even at the non-machining time in which a spindle has no workpiece attached thereto.
Therefore, in the conventional machine tools, when rotating the spindle having no workpiece attached thereto, there is sometimes a case where the machining-area opening is opened by the door slid in the lateral direction and, at the same time, a separate cover member having an attachable/detachable structure is attached to the machining-area opening to thereby allow the observation of the inside during the rotation of the spindle. Here, the cover member is used in the state when having no workpiece attached, in which no blow will be given by the workpiece, so that the cover member is not necessary be so staunch in structure. Therefore, the window can be formed to have a larger size, so that the inside can be observed easily and surely.
However, in the case of the structure where the cover member is attached to the machining-area opening, the attaching/detaching work of the cover member is laborious and a space to dispose the detached cover member is additionally required, leaving problems.